This invention relates generally to systems for generating signals, and more particularly, to systems providing a multi-frequency signal source and frequency synthesis.
High spectral quality signal sources with fast frequency agility, to provide multiple frequency signal sources, may be required in, for example, a variety of radar, communications, electronic warfare and instrumentation applications. Known multi-frequency signal sources, or frequency synthesizers, typically include local oscillators that must provide stable, spectrally clean signals with rapid frequency agility. In operation, these multi-frequency signal sources may be variably tuned to a particular frequency (e.g., frequency shifting) to provide a signal source at that tuned frequency.
These known signal sources generally require wideband or broadband voltage controlled oscillators (VCOs), complex architectures or signal multiplication. For example, known multi-frequency signal sources use complex phase-lock loop architectures or frequency multiplication to provide multiple output signal frequencies.
More particularly, known multi-frequency signal sources providing multi-frequency signal generation typically use a VCO with frequency multiplication. Broadband frequency multiplication requires a high quality VCO capable of frequency set-on accuracy in order to avoid false locking. Frequency step size also is limited to integral multiples of the reference source. Further, direct frequency multiplication is often implemented in association with a step-recovery diode that requires amplification of an input power reference to a level sufficient to efficiently generate desired harmonics. Further, multi-section band pass filters are needed to reject adjacent reference line frequency components.
These multi-frequency signal sources, because of the components used, typically require a higher DC power consumption and/or more complex signal filtering to generate their signals. Also, the broadband VCOs used in these signal sources are less stable, thereby resulting in signals that are not of a high spectral quality. Additionally, these signal sources also often require heat sinks because of the heat generated from the higher power components.